Duplex steam motor



1, cs. E. CAMPBELL 2,216,639

DUPLEX STEAM MOTOR Filed Aug. 10, 1936 5 Sheets-Sheet l Oct 1940- G. E. CAMPBELL DUPLEX STEAM MOTOR Fil ed Aug. 10, 1936 5 Sheets-Sheet 2 it M C: 1| 1| I I Oct. 1, 1940. E. CAMPBELL 2,216,639

DUPLEX STEAM MOTOR Filed Aug. 10. 1936 5 Sheets-Sheet I5 Oct. 1, 1940. G. E. CAMPBELL 2,216,639

DUPLEX STEAM MOTOR v Filed Aug. 10, 1936 5 Sheets-Sheef4 Jjzbf '9 .3111"; g ;l-= I l 4 arrow, 8

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DUPLEX STEAM MOTOR- Filed Aug. 10, 1936 5 Sheets-Sheet 5 Patented Oct. 1, 1940 DUPLEX STEAM MOTOR GeorgeE. Campbell, Chattanooga,Tenn., assignor to The Wheland Company, Chattanooga, Tenn.,

acorporationof Tennessee If 1 ApplicationAugust '10, 1936, Serial Nd. 95,291

1 Claim. (01. 121-114) This invention relates to; an improvement in duplex steam motors, and is more particularly directed to the steam end of a direct-acting duplex steam pump.

In my former patent, No. 2,037,697, granted April 21, 1936, on Duplex steam motors, provision was made for the location of the exhaust valves for the motor below the cylinders in order to drain condensation from the cylinders through the exhaust valves. However, the intake valves were above the cylinders, separate from'the exhaust valves, which required more mechanism to build than if these were unitary.

The object of the present invention is to simplify the construction of the motor, reducing the number of moving parts, and providing a cheaper construction than that set forth in my prior patent, while at the same time obtaining the advantage of draining condensation from the cylinders through the valves.

This is accomplished by the provision of one valve for each cylinder, so constructed that it will control the admission and exhaust of steam from the cylinder, .and will be located adjacent the bottom of the cylinder so that any Water of condensation occurring in the cylinder will flow freely by gravity from the cylinder through the valve, thus providing a self-draining engine or steam end of a duplex pump.

The difference between a steam cylinder for an ordinary steam engine and a steam cylinder for a direct-acting steam pump is that in the steam engine the live-steam ports and the exhauststeam ports may be the same, whereas in a steam pump it is customary to use four steam ports for each cylinder; the two ports nearest the extreme ends of the cylinder are used for the admission of steam, while the two ports spaced from the ends are used for the exhaust. The reason for this is that the piston is stopped at each end of its stroke by the steam action or compressionoccurring after the piston passes over and closes the exhaust port.

When the motor is stopped, the steam trapped in the cylinder condenses and forms water therein, which may be increased by leakage of valves. Upon starting up the motor, this water which has accumulated in the cylinder is objectionable and very often causes breaking of cylinder-heads when the piston comes back thereagainst with considerable force. By locating the valves below the cylinders and by having the passageways extend upwardly to the cylinders from the valve chest, the opening of the valves immediately causes the water to be drained from the cylinders, so as to prevent damage to the cylinder heads,

and also prevent interference with the proper operation of the pump.

A preferredembodiment of this invention is illustrated in the'accompanying drawings, in

which: l

Fig. 1 is a side elevation, partly in section, through a duplex steamlpump; r

Fig. 2 isa top plan view of the steam end of the pump;

Fig. 3 is an end elevation thereof;

Fig. 4 is avertica-l transverse sectional view through the steam endsubstantially. through the mid-portion thereof;

Fig. 5 is a detail transverse sectional view through one of the valves, at the point of admission;

Fig. 6 is a longitudinal sectional view through one of the valve sleeves removed, showing the valve therein and partly in elevation;

Fig. 7 is a rear elevation of the lever mechanism for operating the valves andFig. 8 is a transverse vertical section on the line ti -8 of Fig. 2, the lefthand end of the line being through the steam end, and the right-hand end of the line through the exhaust of the pump.

The invention is shown as applied to a duplex steam pump designated P in Fig. 1, while the steam end of this pump which forms the subjectmatter of this invention is designated E.

This steam end of the pump comprises a pair of parallel steam cylinders l and 2, in which are mounted pistons 3 and 4, respectively, connected directly with connecting-rods 5 and 6, which connecting-rods operate through a cradle 1 and extend to the usual pump pistons located in the pump end of the duplex steam pump.

A valve chest 8 is formed in the lower portion of the steam end below the cylinders l and 2, and is provided with intake and exhaust chambers 9 and [0, respectively, each of which communicates with both cylinders. Passageways l I extend upwardly to opposite ends of each cylinder and form the intake passageways, while passageways I2 are spaced inwardly slightly from the passageways I l and form the exhaust passageways. The exhaust passageways l2 are spaced inwardly from the ends of the cylinder further than the passageways I I in order to trap some of the'steam in the end of the cylinder to act as a cushion for the piston, particularly when the invention is used in connection with a duplex steam pump where this action is desired.

Mounted in valve openings l3 in the valve chest 8 are sleeves l4 having openings 0 arranged therein for communicating at opposite ends with the intake steam chamber 9 and at an intermediate point with the exhaust steam chamber I0. Communication through the sleeve M with the respective passageways and chambers is controlled by valves 5 and [6 for the cylinders and 2, respectively. The valves [5 and I6 are of the usual balanced piston type, and are connected, respectively, with valve-stems l1 and IS, on which the piston-valves are fixed against lost motion. However, there is lap on the valves for properly timing the admission and exhaust of steam.

The valve-stems l1 and l8 are operated by the usual cross-over lever arrangement, except that it is inverted and secured beneath the cradle 1. In this position, the supporting stand I9 is fixed to the under side of the cradle and has cross-shafts 20 and 2| journaled therein, as shown in Fig. 7. The shaft 20 has at one end a lever 2| carrying a roller 22, which operates within a spool 23 fixed to the connecting rod 5. The opposite end of the shaftZfl has a rocker-arm 24 fixed thereto and connected with the valvestem l8. The other cross-shaft 2| carries an upstanding lever 25 with a roller 26 operating in a spool 21 fixed on the connecting-rod 6. The opposite end of the shaft 2| has a rocker-arm 28 thereon connected with valve-stem [1. Thus the piston 3 reciprocates its connecting-rod 5 to operate lever 2|, shaft 20,-iocker-arm 24, and the valve-stem I8 for the other cylinder, which encloses the piston 4. In turn, the piston 4 controls the valve for the cylinder I through the cross-over arrangement described so that the piston of one of the duplex cylinders operates the valve of the other cylinder.

The valve chest may be provided with suitable steam inlet and exhaust openings, the former of which may be in the top or the side, and the latm ter in either side or bottom. The steam inlet is shown at 29 between the cylinders for supplying steam to the steam chamber 9 the steam on entering flowing beneath the walls b in opposite directions, while the exhaust is shown at 30 in the bottom of the chamber In, although provision is made for exhausting steam through .either of the lateral outlets 3| or 32 upon the removal of the respective cap therefor.

Thus it will be seen that the live steam enters at a point above the exhaust, and the condensation passes out through the bottom of the pump, by gravity, its passage only being impeded by the valves in the lower portion of the pump.

The provision of a single combined intake and exhaust valve for each cylinder simplifies the construction and operation, and cheapens the manufacture, and yet by locating the combined intake and exhaust valve below the cylinder it will control the admission and exhaust of steam and will be located in such position that any water of condensation which may occurin the cylinder will flow downwardly through the passageways by gravity and be exhausted from the cylinder, thus providing a self-draining steam end in a duplex pump, of simple construction and operation.

I claim:

The combination of steam cylinders, valve chests extending parallel therewith, separate unobstructed passageways for the admission and exhaust of steam leading downwardly from the cylinders and into the valve chests therebeneath, piston valves located in the valve chests, a steam intake chamber located between and below the cylinders and extending downwardly and branching toward each end of the cylinders and connecting with the outer endsof the valve chests, a chamber for the exhaust steam connecting the valve chests and provided with a suitable outlet below the valve chests, the combined steam and exhaust chambers being so located and arranged that the valves present the only obstruction to the free flow downwardly by gravity of the condensation to the exhaust and away from the pump without entering the cylinders, and means for operating the valves.

GEORGE E. CAMPBELL. 

